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Zama C1U rebuild question

Discussion in 'Mechanic and Repair' started by abl1111, Jul 28, 2010.

  1. abl1111

    abl1111 LawnSite Member
    Messages: 16

    Carb rebuild question:

    I'm rebuilding a Zama C1U. Where the pump cover is concerned - the kit comes with an extra part, almost like a pc of plastic that matches tha gasket and the pump diaphram - but the ZamaCarb website illustration does not mention anything about it ?

    Also, the directions mention installing a fuel strainer in the metering chamber, the kit comes with this strainer, but I don't see where it goes. There was no visible 'old' strainer when I took it all apart unless it's under a plug somewhere ?

  2. dutch1

    dutch1 LawnSite Silver Member
    from Jayhawk
    Messages: 2,249

    A rebuild kit will normally cover several carburetors so having extra parts is not unusual. Pick out the ones that match up with the ones from your carb.

    The screen will be found in a recess in the carb, the port being about 1/4". The screen is probably about 3/16 below the surface. It can be removed by a pick and reinstalled with rod of slightly less diameter than the port. It is pretty fragile so full circumferential support when installing is helpful.
  3. MowerMedic77

    MowerMedic77 LawnSite Bronze Member
    Messages: 1,164

  4. ricky86

    ricky86 LawnSite Silver Member
    Messages: 2,122

    That piece of plastic is also a diaphragm. That particularly one is far and away more durable than the rubber one. It will pump less fuel though. The strainer that comes in the kit is on the pump side.
  5. abl1111

    abl1111 LawnSite Member
    Messages: 16

    Rebuilt carb without removing any of the welch plugs.

    I installed the fuel filter screen - there definitely was none in there when I
    opened it up.

    Put it on and it runs GREAT !

    Now, I have to put a load on it and see if it works for more than 10 minutes !

    In the past, she would loose power and then stop running and be impossible to re-start. When I checked the spark plug - therre was NO fuel - so hopefully the carb rebuild was the ticket.
  6. abl1111

    abl1111 LawnSite Member
    Messages: 16

    Hmmm.. Question...

    I rebuilt this carb and it runs great - but after 15 minutes or so, while under load, she loses power. As soon as I even touch the "H" setting screw on the carb ( not even turn it ), it will come right back up to full power and run great again !?

    Any advice ?

  7. abl1111

    abl1111 LawnSite Member
    Messages: 16

    bump - any advice would be appreciated
  8. sharkey

    sharkey LawnSite Member
    from Pa
    Messages: 50

    It could be that your fuel tank vent is not opening causing the tank to hold a vacuum from the fuel being used. The test for this is to open the tank cap when the problem occurs. If it runs good once you have burped it so to speak then you know where the problem is. Otherwise the metering lever may be too low and when you open the high jet the extra fuel it draws pulls open the needle valve under the diaphragm lever allowing the engine to run until the metering side runs dry. Check the tank vent by probing it with a tag wire. If that doesnt do it, raise the lever a little. If you get the lever too high it will flood so you will know what to look for. Pay attention to the orientation of the gaskets to the diaphragms when you put the carb back together. On the metering side the gasket goes down first against the carb body, then the diaphragm and then the cover. On the pump side the diaphragm goes down first with the gasket above it and then the cover.

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